One aspect of the British public health campaigns in the field of the sexual transmission of HIV/AIDS has encouraged people to ‘get to know their partners’. This article draws on interview material (n = 95) to explore the extent to which such advice is followed amongst young people in relation to first‐ever intercourse. There was very little evidence that attempts are made to assess HIV risk factors in prospective partners, and a number of powerful reasons for not doing so emerged. Time to intercourse since becoming ‘a couple’ was 2 weeks or less for half the sample and within 24 hours for a quarter. Roughly equal proportions of respondents knew their partner's sexual status, assumed their sexual status or knew nothing. Condom use was more frequent amongst older females who progressed to intercourse later in relationships. The implications of the results for HIV/AIDS interventions are discussed, as well as some problems with health belief models based on notions of rational decision‐making.